An amphibious vehicle includes, for example, an engine that serves as a power source, a power transmission means for transmitting a driving force from the engine, a land traveling means, and a water traveling means. The power transmission means is propeller shaft or the like which transmits a driving force from the engine. The land traveling means is a wheel, a crawler belt, or the like driven by the driving force transmitted from the engine via the power transmission means. The water traveling means is a water jet mechanism, a screw, or the like driven by the driving force of the engine switched from the land traveling means.
In an amphibious vehicle, when a water jet mechanism is employed as the water traveling means, the amphibious vehicle travels (glides) on water at a high speed by propulsive force of the water jet from the water jet mechanism. In addition, when the water jet mechanism is employed as the water traveling means, when moving onto land from water, it is possible to smoothly shift to ground travel (self-run) by switching to the driving of the land traveling means.
A hull (vehicle body) of an amphibious vehicle disclosed in Patent Document 1 has a double bottom structure including a first ship bottom and a second ship bottom. In this amphibious vehicle, gear boxes such as a propeller shaft and a differential gear are installed in a space between the first ship bottom and the second ship bottom. The space is open at the front surface and rear surface of the hull.
An amphibious vehicle disclosed in Patent Document 2 includes a vehicle body, a water jet mechanism, and a water-cooled heat exchanger. The water jet mechanism includes a water jet channel and a propeller which has an impeller and a shaft. The water jet channel includes an inlet formed in a bottom surface of the vehicle body and an outlet formed in a rear surface of the vehicle body. The impeller of the propeller is provided in the water jet channel. The shaft of the propeller transmits the driving force of the engine to the impeller. The impeller is driven by the power of the engine, and takes in water from the inlet and discharges the water as a water jet from the outlet when traveling on water.
The amphibious vehicle in Patent Document 2 includes a cooling water passage for sending water to a water-cooled heat exchanger. The cooling water passage includes a cooling intake port which is open on the outlet side of the impeller in the water jet channel. In this amphibious vehicle, water from the cooling water passage, engine cooling water, hydraulic oil, or the like is cooled by a water-cooled heat exchanger.